[gobject-introspection] block can be None, fixup last commit

[Johan Dahlin <johan src gnome org>]

commit 754e5462f6dfbe3793eb959abf3dbfa7d2fe6435
Author: Johan Dahlin <johan gnome org>
Date:   Tue Oct 5 21:34:39 2010 -0300

    block can be None, fixup last commit

 giscanner/maintransformer.py |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)
---
diff --git a/giscanner/maintransformer.py b/giscanner/maintransformer.py
index 9053abf..a55fdf4 100644
--- a/giscanner/maintransformer.py
+++ b/giscanner/maintransformer.py
@@ -411,9 +411,10 @@ usage is void (*_gtk_reserved1)(void);"""
                 "Unknown container %r for element-type annotation" % (node.type, ))
 
     def _apply_annotations_enum(self, node, block):
-        enum_type = block.options.get(OPT_TYPE)
-        if enum_type and enum_type.one() == 'bitfield':
-            node.__class__ = ast.Bitfield
+        if block:
+            enum_type = block.options.get(OPT_TYPE)
+            if enum_type and enum_type.one() == 'bitfield':
+                node.__class__ = ast.Bitfield
         self._apply_annotations_annotated(node, block)
 
     def _get_transfer_default_param(self, parent, node):